Sorry for the late reply but thanks for the info, Victron also makes a 5000VA (4000ish W) 48V multi plus 2 as well, but I'll look at the specs on Conext as well.
So I bought an off grid lake property, cottage is wired for 120V AC and is run by a small solar array ( not sure of the config but 2x 150w and 2x 90w ). The battery bank is 8 6v FLA's that are over 10 years old and won't hold charge. There is Pro Star PS 30 Charge controller, Iota DLS 55/IQ4...